The field of the invention relates to x-ray devices and more particularly to x-ray devices capable of both imaging and therapy.
X-ray devices used for imaging and/or therapy are known. In the case of imaging, such devices are typically arranged to provide an x-ray source and detector on opposite sides of a body of a patient. The source and detector rotate in unison around the patient collecting x-ray data at discrete locations.
Typically the x-rays are allowed to propagate through the body of the patient in the form of a fan beam. The detectors of a fan-beam device form an array of many individual detector elements, often arranged in the form of an arc to detect x-rays along the spread of the fan beam.
In several scanner models, the x-ray beam is wider in the direction normal to the fan (and may then be referred to as a xe2x80x9ccone beamxe2x80x9d) and is detected by multiple rows of detectors or by a so-called area detector.
In operation, the source and detectors are rotated continuously around the patient, and the signals from the detectors are sampled at intervals of a few milliseconds, so that sets of x-ray absorption profiles are collected at many angular increments around the patient.
From the x-ray data, an associated computer may solve a matrix of equations, or use some other mathematical technique to obtain a measure of the x-ray absorption of each of a number of two-dimensional areas (or xe2x80x9cpixelsxe2x80x9d) within a finite thickness of the slice. The pixels may be combined to form a two-dimensional image of a cross-sectional view, or slice, through the patient""s body. The patient may then be moved a small distance in a direction normal to the plane of the slice, and the process of x-ray exposure, data collection, and computer data reduction may be repeated to obtain an image ofan adjacent slice. The motion and process may be repeated any number of times. Alternatively, the patient may be moved continuously, so that the x-ray beam follows a helical surface within the body. In devices employing a cone beam, several slices may be generated simultaneously.
By associating the data of adjacent cross-sectional slices, a three-dimensional array of data may be obtained. From the three-dimensional array of data, three-dimensional images (or two-dimensional images at orientations different from the slices) can be created, which may be used to determine the location of tumors or other lesions.
Once tumors or other lesions have been identified, the tumor or other lesion may be treated by irradiation. While some, more recent x-ray systems, allow for both imaging and therapy, most x-ray systems do not allow such dual functionality. Further, even where both imaging and therapy are allowed, the effectiveness of such treatments requires careful positioning of the patient to maximize the effectiveness of the therapy on a target tumor or other lesion while minimizing damage to surrounding tissue. Accordingly, a need exists for a device that allows both imaging and therapy that accommodates the vagaries of target location.